/*  
  -- The Lime II Project -- 

  A tuplespaces-based middleware for coordinating agents and mobile hosts.
  Copyright (C) 2005.
  Gian Pietro Picco, Amy L. Murphy, Lorenzo Bellini.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received this copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 
*/

package lime2;

/**
 * A facility for synchronizing a thread.  
 * 
 * @author Gian Pietro Picco
 * @author Amy Murphy
 * @author Lorenzo Bellini
 */

public class Lock 
{
 // private data member
 private int clicks = 0;	
 
 /**
  * Suspends the thread on this instance.
  */ 
 public synchronized void hold() 
 {
  // maybe if the thread is interrupted, we want something else to happen 	
  try { wait(); } catch(InterruptedException ie) { ie.printStackTrace(); }  
 }

 /**
  * Sets the number of times that method "release" must be invoked before the suspended thread is resumed (default is
  * one).
  * 
  * @param n number of "clicks"
  */
 public void setClicks(int n)
 {
  if (n <= 0) throw new IllegalArgumentException("number of clicks must be greater than zero");
  this.clicks = n;
 }
 
 /**
  * Resumes one thread suspended on this instance.
  */ 
 public synchronized void release() 
 {
  if (clicks > 0) clicks--;	
  if (clicks == 0) notify();
 }

}
